LateralDamping, etc.

#1 I would ASSUME, (but you could look in core code maybe) that lateral damping also damps forces when they are external or for other reasons are not from the lateralforce field in the datablock, and therefore not pointless. but maybe they are indeed pointless :)

#2 Force acts against a "deflection", damping acts against a "deflection rate".

In oscillating systems (for example "spring mass damper" systems like the torque wheeled vehicle physics), the damping causes the reaction to a disturbance to die out over time. Without lateral damping in the tires, if you blipped the steering or bumped the car, the vehicle could oscillate back and forth forever (ideally). With damping, the oscillations should die off over time. For the same reasons, the Torque suspension springs also have damping (like your car has shock absorbers - US term for the automobile part that provides suspension damping.) (This is a very simplified description that isn't perfectly correct or complete.)

Too much "damping" relative to the "force" can easily make the suspension unstable such that the oscillations increase rather than dying out over time as desired. Instability can happen both because of the constants chosen, and also how they react given the fixed tick rate of the stock Torque vehicle system (if you make your "force" too large in relation to the mass, your system will be too stiff: it will tend to oscillate too fast (too high a frequency) to be properly modeled at 32 ms between ticks.) Modeling a "sports car" with true-to-life response rates in stock Torque would put you near the edge (if not over it) for that tick rate. Modeling a quick acting Formula One car would likely find this effect to be a serious issue.

If you don't want to just play around with the datablock fields until something works, there are engineering procedures to design modeling constants like this to result in desired oscillation characteristics, but they require a basic background in mathematics and physics that is university level to use. Less technical "cookbook" methods have grown up since people started building automated control mechanisms in the 1800s. Google "Controller Tuning". (You will see a lot about "PID". P (proportional) is the "force", D (derivative) is the damping.)

#3 Oh okay.

So you are saying that if I set the following, these are the results?
High force, no damping = large infinite oscillation
High force, damping = large oscillation, but fades
Low force, no damping = small infinite oscillation
low force, high damping = stiff

Am I understanding correctly?

#4 The force doesn't necessarily affect the size of the oscillation. The force determines "how stiff the spring is". If you pull a spring back a certain distance and let it go, it will oscillate. Without damping, both high force and low force springs will oscillate between the same positions in this situation when started the same (same oscillation amplitude) - the stiffer spring will just oscillate faster (at a higher frequency).

The Wikipedia vibration article is a start to getting a feel for the use of damping:
http://en.wikipedia.org/wiki/Vibration

I would say, rather:

High force, no damping = fast oscillation, doesn't fade
High force, some damping = fast oscillation, but fades
Low force, no damping = slow oscillation, doesn't fade
low force, high damping = slow oscillation, fades quickly or so quickly that it doesn't even look like an oscillation at all


I'm just starting to play with the Torque wheeled vehicle physics. My first problem is getting familiar with the units used. (For example, the "force" datablock field value for the suspension springs seems to be in units of the entire deflection, rather than something like Newtons per meter of deflection.)

#5 Better Wikipedia page might be:
http://en.wikipedia.org/wiki/Damping


The Vibration page is pretty technical, but does have a nice graph showing how damping can reduce the amplitude of the oscillations:
http://en.wikipedia.org/wiki/Image:Damped_Free_Vibration.png

#6 Oh okay that makes much more sense. Thank you.

So the force of the springs is based on how they are affected by outside influences, such as terrain, gravity, etc.

Does anyone know what units these values are in?

Thank you again, Matthew :)